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NBN planner critiques 121-point design

Concerns the network will be less resilient.

A key designer of the National Broadband Network has publicly criticised the regulator-mandated requirement to build 121 points of interconnect, claiming it reduces the network’s resiliency.

Peter Ferris, general manager of design and planning at NBN Co, told attendees at the annual Australian Network Operators Group (AusNOG) conference this week that the mandate would result in a greater number of services being affected by any one weakness in the network.

He said the wholesaler had worked to build redundancy where possible into the network. Geographically diverse fibre paths had been scheduled for installation between each point of interconnect (or “aggregation node”) and fibre access node, as well as a manually patched diversity between each node and the fibre distribution hub which would ultimately connect to premises.

Though homes would receive a single fibre path without redundancy on that element, NBN Co had planned to offer point-to-point services to large enterprise as one of multiple product drops to be introduced in coming years. It had begun leaving approximately 24 fibres in every 200 for each fibre distribution hub for specialised business services.

“When we move into our business-grade services, the architecture that’s been put in place allows the provision of a geographically diverse path from any location in a fibre distribution area back to the FAN site,” Ferris said.

However, a mandate last year from the Australian Competition and Consumer Commission - and accepted by government - required all premises served by fibre, fixed wireless or satellite products on the NBN to be addressed at a single point of interconnect.

The ACCC mandated NBN Co build 121 points, or aggregation nodes, to promote backhaul competition. It over-rode NBN Co’s own proposition at the time to build two redundant points of interconnect in each of seven major areas across the country.

The ultimate decision led to the NBN having “121 single points of failure”, according to Ferris, who is commonly credited with having formulated the 14-point plan.

The mandate meant that, should a single point of interconnect go down, it could potentially disrupt services to up to 150,000 premises.

His criticism echoed similar comments made among potential access seekers, including Internode regulatory affairs manager John Lindsay, who told a Senate inquiry into emergency communications last month that the plan could dilute the NBN’s effectiveness in event of a natural disaster.

“It does not make a lot of sense when you talk to network engineers, who actually design for building resilient telecommunications networks, because they look for a lot of physical redundancy,” Lindsay said at the time. “They want a function that can be performed at one location to be able to be performed at a second and, ideally, even a third location, so that if a physical location is unavailable that function can be performed somewhere else.

“They are also trying to make sure that when one location fails that it does not take out millions or hundreds of thousands of services. Ideally, it will have a fairly localised impact.”

The ACCC’s mandate had stretched to the physical location of the points of interconnect, which in some cases forced NBN Co to split the aggregation node and the point it was designed to house.

“We did not have space to put our aggregation node equipment in all of those locations so we have cases where the point of interconnect and the aggregation node is in different locations,” Ferris said.

The situation had already occurred at the NBN second release site of Riverstone in Sydney’s north-west, where NBN Co was required to place the aggregation node in Richmond and the point of interconnect in Windsor in order to allow easier access by service providers.

The two locations were connected by a single Optical Distribution Frame extension, also covered by geographically diverse fibre routes.

Despite continued consternation around the 121 point plan, the competition watchdog has yet to indicate whether it would be willing to move on the issue.

iTnews understands NBN Co would technically be able to move back to its original, 14-point plan in the future but would require a differing regulatory mechanism from the Federal Government or ACCC to do so.

Despite the network design issue, Ferris believed the fibre being rolled out by NBN Co itself would prove resilient enough to serve Australia for more than 50 years.

He pointed to Verizon’s FiOS fibre rollout in the US as an example of the cable’s resiliency. The project, which had passed 16 million homes to date with fibre-to-the-premises technology, had so far registered a fault rate of 0.9 per 100 services.

That, compared to more than 10 faults per 100 services for the Australian copper access network, meant fibre would prove a more effective technology for up to 60 years, Ferris said.

NBN Co had already slated use of 60,000 kilometres worth of existing fibre in regional areas and 5000 kilometres in metropolitan areas as part of the network, much of which would be served through the interim and final deal with Telstra.

The deal would also cover use of 130,000 kilometres worth of Telstra-owned duct space, used where Telstra had combined power and existing infrastructure.

The continued use of Telstra infrastructure, including 900 of the incumbent’s exchanges, would come as relief to service providers, Ferris said, as “the reliability of that infrastructure is currently well known in the industry”.

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